If this is correct, would the folks concerned about too much horsepower for the 9A still be concerned?

Probably. Some folks put way too much emphasis on an arbitrary limit that was set in stone and proclaimed to be "The Limit."

Yes, there are reasons to limit horsepower on any aircraft design. No, those limits are not likely to be sharp-edged leading to a "you will die" scenario if you approach 100.1% of that limit. Yes, there will always be people creeping across that line a little, just like we drive too fast on the highways. And yes, there will always be people wagging fingers at those who do it.

Doug, it all depends on what prop you want to put on your -360. As I mentioned above, my O-360 and Catto FP prop is lighter than an O-320 with a metal FP prop. If I put composite CS prop on it, I would still be lighter than a 320 with a metal CS prop, which is approved.

As you build, you once again have to go through the Q&A process to figure out which configuration, options, etc. you want in your plane.

As you pointed out, your -9A with a 160 hp (I)O-320 was a good performer. There is absolutely nothing wrong with that engine.

I have 592 hours on the ECI IO-340. I would not want any other engine on my 9A. Weight on the nose gear was an important factor. So, running the IO-340 with a 3-blade Cato is ideal. The engine turns out to be 8 lbs lighter than a 360 and still has 180 HP. I know the traditional 320 or 360 engines are pretty much the norm for RVs but the 9 does very very well with the IO-340. At least my 9A does! Anyone contemplating what engine to use in the 9 should give it consideration.

It is kind of funny that no one even raises an eyebrow when larger than recommended engines are installed in RV-4, -6, -7, and -8's.

I guess only the -9 will fall out of the sky when over engined.

One thing to keep in mind, and we in the RV world often forget this. The O-320 150 hp Lycoming was designed to lift a four place engine. In our little planes, they are a great choice, if you keep everything light.

When I had the O-290 of all of 135 hp in my RV, it was a GREAT combination. When I would travel with the local RV gang for a couple of hundred mile trip, I would take off first and when I would enter the pattern, the last airplane ahead of me would be just touching down.

The bigger engines really only gain you in ROC and not so much in cruise speed. Even then, 1400 FPM is nothing to shack a stick at.

Lots of good info on this and related threads. After shopping for both O-320 and O-360 used engines, I found a deal on an O-320 that was a fresh rebuild on the lower end with no cylinders, which was what I was looking for. I just received my new Lycoming cylinders and will start the assembly process as time permits. The money saved compared to a new engine will go a long way towards the panel I want. Thanks for all the responses. I am sure we all learned something about engine choices in this thread.

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